Recently, a wireless power transmission or a wireless energy transfer for wirelessly transferring electric energy to desired devices has been actively researched and developed.
In order to use the wireless power transmission, a transmitting terminal for transmitting wireless power and a receiving terminal for receiving the transmitted wireless power may be provided.
Meanwhile, if the wireless power is indefinitely supplied to the receiving terminal, the receiving terminal may be damaged. Especially, an object to be charged may be damaged due to over voltage.
In this regard, a technique for controlling the charging of the receiving terminal is disclosed in U.S. Pat. No. 8,217,621.
However, according to the above patent document, a power generating unit, which has a complex structure to generate a predetermined low-voltage power supply, is necessary so that the charging control is inefficient.